(1) Field of the Invention
The present invention relates to the production of a magnetic powder for use in the magnetic recording. More particularly, the present invention relates to a process and apparatus for the continuous production of a cobalt-modified magnetic iron oxide powder by which a high-density recording is made possible.
(2) Description of the Related Art
As an example of the process for the production of cobalt-modified magnetic iron oxide particles, there can be mentioned a process comprising dispersing magnetic iron oxide particles in an alkaline solution and adding a cobalt salt along or together with another component such as a ferrous salt to the dispersion to form cobalt modified magnetic iron oxide particles. According to this process, a cobalt-containing layer is formed on surfaces of magnetic iron oxide particles and the magnetic characteristics are improved. For example, the coercive force and the saturation magnetization per unit weight are increased. The thus-obtained cobalt-modified iron oxide particles are very suitable as the magnetic powder for magnetic recording.
The conventional process for the preparation of such a cobalt-modified magnetic iron oxide powder for the high-density recording is a batchwise process in which the whole reaction is completed in one reaction vessel.
This conventional batchwise process is defective in that the reaction time is very long and the operation efficiency is low.